The other night, as I was walking on the Hill, I saw a guy pedaling his bike in the opposite direction. He wasn’t alone. A pair of arms rested on his shoulders, and a tiny head poked out next to his helmet. Was it a kid getting a piggyback ride? Nah. An alien? Unlikely.

Then the duo got close enough for me to make out the passenger: It was a dog, with its hindquarters happily tucked in the cyclist’s backpack.

“My 50-pound husky couldn’t do that,” announced the astonished woman on the street corner next to me.

It’s not that odd that pet owners want to transport their furry friends on bikes — more people are cycling generally. And if your pooch prefers fresh air, it can be a pleasant way for both of you to travel. Sean Prichard, president of D.C.’s Pant & Wag, which offers fitness adventures for dogs, says as long as the pet is well behaved, a bike works beautifully. He recently spotted a calm Jack Russell terrier chilling in a basket — E.T.-style — in Logan Circle.

Prichard’s only concern is safety. A dog that decides to bolt from a bike will wind up in the middle of traffic, so it’s imperative that owners know what they’re doing, he says. And that doesn’t seem to be the case for many of the people he’s seen riding bikes alongside their leashed dogs.

Whose feline is it anyway Metro’s policy: Service animals can ride unconfined; all other creatures must be in secure containers. Zipcar has the same rules — but one kitten must not have gotten the memo. A Zipcar employee was cleaning a vehicle when a gray and white tabby popped out from the backseat. No one who’d rented the car claimed the feline. So it was adopted through the Washington Humane Society, says Zipcar D.C. general manager Scott Hall. No word on whether it’s named “Zippy.”